Hot isostatic pressing (HIP) is a form of heat treatment that uses high pressure to improve material properties. That pressure is applied by an inert gas, usually argon. Time at elevated temperature and pressure allows plastic deformation, creep and diffusion to occur. Castings for critical applications are HIPed to eliminate internal microporosity thereby improving mechanical properties by removing defects. Hot isostatic pressing also enables the bonding, or cladding, of two or more materials together, either in the solid or powder form and it is this aspect that is of interest for nuclear cleanup.